PhenomII x4 840 vs. PhenomII x4 955 (Black edi.) :What shoul I Go for?

The price of Phenom II 840 is 4.8K and Phenom II X4 955 is just 5.4K. Street price may be lower for both. So I suggest you to grab the Phenom II X4 955.
The reasons are

i. 955 is a true Phenom II processor having 6 MB of L3 cache. Phenom II 840 is just a rebranded Athlon II processor without the L3 cache. So 955 performs better in gaming and lots of CPU intensive works

ii. 955 is a Black Edition processor. So it has unlocked multiplier and can be overclocked to very high level by just increasing the multiplier value. 840 is not a B.E. CPU and for overclocking the voltage, core clock speed etc need to be updated which are not very easy task.

I think you are right. Thanx 4 helping

Yep its a no brain choice.

Go with Phenom X4 955 BE. I also have the same and it rocks. OCing it is a child's play.